Sound-box for sound-reproducing machines



p 1932- I R. GOLDSCHMIDT 1,878,770

SOUND BOX FOR SOUND REPRODUCING MACHINES Filed Jan. 14, 1932 I? .7/7 van/0 0 [0Z5 CZ 2 $12:

Patented Sept. 20, 1932 rwnoLr GOLDSCHMTIDT, or BERLIN-CHARLOTTENBURG, GERMANY SOUND-BOX FOB SOUND-REPRODUGING MACHINES Application filed January 14, 1932, SerialNo. 586,661, and in Germany January 13, 1931.

This invention refers to improvements in sound-boxes for sound-reproduc ng machines and is designed for the, type, where the record-grooves are utilized for feeding the sound-box across the record. 1

'The invention is applicable to mechanical as well as electrical sound-boxes, in the first instance a diaphragm, in the latter an armaturebeing actuated by the stylus-bar.

Insound-boxes for sound-reproducing machines of the type where the record-grooves feed the sound-box across the record usually,the stylus-bar is fixed on the case of the sound-box pivotally or by means of springjoints. When the stylus actuates the diaphragm by employing the stylus-bar as a lever,back-pressure is exercised upon its bearings, pivots or springs, with the effect of causing vibrations of the sound-box as a whole as well as the tone-arm. Springq'oints moderate'these vibrations at the expenseof volume and accentuation. v

According to the present invention the stylus-bar is connectedwith the sound-box masscontained in this push-weight being so great that even at comparatively low frequencies it is suflicient to take up the backpressure by the dynamical reaction of its mass, its: impedance. suspended in such a'flexible way,that it can easily move and fulfill its purpose as a floating mass.

One object of this invention is to reduce to a minimum the undesirable vibrations.

of the sound-box as a whole and the tonearm.

The push-weight is box embodying my invention.

Another object is to increase the volume of the sound instead of diminishing itby taking up the back-pressure in bearings or ordinary spring-joints. This efiect is caused by the phenomenon that the push-weight vibrates in an additive co-action with themovements. of the stylus. i

A third object of this invention is to extend the response-curve further into the bass, in other words, to use the push-Weight for tuning the diaphragm to a frequencybelow 500 cycles per second.

A fourth object of this invention is to make the sound less metallic and more musical than with ordinary sound-boxes. This result is obtained, because the-turning. point of the stylus-bar and therefore its ratio, of." transformation as a lever, is not definite any more, but varies with the frequency.

The push-weight may be either fixed to or embodied in .the stylus-bar or pivotally joined wit. The latter form is preferred, because with rising frequencythe stylus-bar gradually and automatically will shake ed the mass of the push-weight to the extent as its impedance increases and use the pivots as turning point. At high frequencies the push-weight stands practically still and the stylus-bar turns in its pivots only. The accompanying drawing illustrates the invention by way of examples. For the sake of showing the principle of the invention .more clearly the drawing has been given a schematical character. o

Fig. 1 is a section through a sound-box, no springs being used for transmitting the feeding pressure.

Fig. '2 is the section of a sound-box, where i the feeding pressure is transmitted-through rubber buffers or springs. a

Fig. 3 is afront View of the latter examle. T p Fig. 4 is an example of an electrical sound- In Fig. 1, A isthe case of the sound-box,

B the diaphragm, the centre of which is connected to the stylus-barD by the coupling spring C. Through the pivots E the pushweight M is joined to the stylus-bar D, the

latter being connected to the body of the sound-box A through the pivots F.

It is to be understood, that in any case the pivots indicated may have theform of proper bearings with or without balls or may assume the form of spring-joints.

In Figs. 2 and 3, A is the case of the soundbox, B therdiaphragm,iD the stylus-bar con? nected tothecentre'of the diaphragm Bbyj means of the spring C. The stylus-bar D I is again. joined to the push-weight M through the pivots E? A connection between the push-welght M andthe sound-box A is established close to the centr'eoft he diaphragm through arms M, sothat turning moments are avoid'e'd'and amore perfect elimination othe(;.undesirable vibrations of the soundbox is agwhole is effected. For this purpose,

a .bridge, N .;-is fixed across. the 'sound-box. Thepivots. F andrthefibuffers or springs H g serve to transmit the feeding-pressure from arm-s Mi? -,-The pivots F maybe omitted with suitable construction of the. bufiers or springs I-L;.-,, The latterare exceedingly flexible, becausethey arersituated at a very small radius. ,1The*-pushweight M is dividedinto two portions ,suspendedon opposite sides of the stylus bar D as shown. IThear-ms Mr rextend downwardly from thevbridge N parallel to? the. stylus bar and connect with the two agz portions'sof thelpushrweight I F igAis thevertical-section ofan electrical sound+box, Nf-beingrthe-magnet, O the induction-coil, W the varmature forming part 4 ;isuj-oinedto ther stylus-bar D- by the-pivot E and! issupported by depending arm 7M. K

and aP-rare-rubber springs. By F andG a ball bearing. is indicated of such a construction that. play ,is-allowedto the push-weight 45,- Methrough; arm..-M5, so -that the latter can carryout rotary movements not only round its rzpointoof suspension, but also-round the centreaof gravitynS, aswell as. lateral movements, so tha-tait may assume-various modes so of, motion; i I

Whatisclaimed is: r 1. 2 In. a ssound=box r for sound-reproducing machines ofcgthe :type-. where the record-' grooves are utilized forfeeding. t-hersound-v li aboxacross-the .record, a mechanically displaceable-element, a yielding stylus-bar connectedtherewith and a push-weight connected with sa1d mechanically displaceable elementandpivotally connectedwith thestylus-:

00 bar;

2. 111 a .sound.=box for sound-reproducing machines of the type where the record grooyes, are: ut1lized for feeding the soundbox across the record a'mechanicallydis-i placeable-elemen t, a yielding stylusbar coniromthe connection of said i'stylusbar :witbfl 7 said 7 bridge-like iramevon opposite. sides of the dynamical-reactionof the mass of the push-weight. I II II I 45. Sound-boxdor *sou-nd=reproducing machines wheres the record-grooves are utilized for feeding thesound-box across the record comprising ray-mechanically displaceable element, a stylus-bar connected with. said ele ment and yielding'tosuoh an,extent that only a fraction Of'illlG back-pressure is trans:

mitted to said element,.anda,weigh ted 5611777 dulumxconnected with said element and pivotally connected withsaid-stylus barr' 5. 4 Sound-box for sound-reproducing. ma; chines where the record-grooves are utilized; for feeding the. sound-box across the record, a vibratory member in: saidsound-box,.az stylus-bar connected with said member a" weighted pendulum connected withsaid 'vibratory Vmembers. and pivotallyconnectedi with. said; stylus-bar Y whereby said stylus-bar yields to such an .extentthat itscompliance r; is greater than the compliance: ofthe; vibr af I tory member; of the stylus-barD4 Thepush-weight M- 6. In a sound-b oX -forsound-reproducing. machines of rthe. type where the record-.19 grooves are utilizedv for .feedingthe sound; box across the record a vibratory member supporting .means for said vibratory membar, a stylus bar connected .with said vibratory member, a weighted pendulum suspend v ed. from, said supporting means, and a pivotal connection between said stylus bar andl I said weighted pendulum at a position remote said vibratorymemberb 1 I a g 7 In a sound-box for .soun'd reproducingg machines ofithe type where the recordgrooves are utilized for feeding the-sounds boxlacross. the. record, :a vibratory me1nber,'. supporting :means'for said vibratory mem-. ber, a stylus :bar connected with .said vibras.w

'tory member, a bridge-like:iirame',yieldingly' v connected with said supporting means, a pair of parallel :bars extending downwardly from .125 said stylus-bar, a weight on theextremityot: each of said-bars, and pivotal connections between said stylus-bar and said parallel bars at aposition remote from the connection of said stylus-bar with saidvibratory member. 7

8. Sound-box for sound-reproducing machines, where the record-grooves are utilized for feeding the sound-box across the record chines, where the record-grooves are utilized for feeding the sound-box across the record with a yielding stylus-bar anda push-weight,

' the push-weight being so yieldingly suspended that it may exerciserotary motions with difierent centers as well as lateral'motions.

10. In a sound box for sound reproducing and sound recording machines, a casing, a

ing to execute parallel as well as pivotal motions, a push weight pivotally connected to 7 stylus bar supported with respect to said casing to execute parallel as well as pivotal motions, resilient elements connected with said stylus bar, a push weight pivotally connected to said stylus bar, said push weight having such a mass that through the back pressure of the stylus bar it is set in vibratory motion at useful acoustic frequencies of the bass range, and through the cooperation of said vibrating mass with the stiflness of the stylus bar and the resilient elements connected thereto, the response within the lower end of the useful acoustic frequency range is increased.

12. In a sound box for sound reproducing and sound recording machines, a casing, a stylus bar supported with respect to said casing to execute parallel as well as pivotal motions, resilient elements connected vwith said stylus bar, a push weight pivotally connected to said stylus bar, said push weight having such a mass that through the back pressure of the stylus bar it is set in vibratory motion at useful acoustic frequencies of the bass range, and through the cooperation of said vibrating mass with the stiffness of the stylus bar and the resilient elements connected thereto, the response for useful acoustic frequencies below 500 cycles is increased.

13. In a sound box for sound reproducing and sound recording machines, a casing, a stylus bar supported with respect to said casing to execute parallel as well as pivotal motions, resilient elements connected with said stylus b ar,'a push weight pivotally connected to said stylus bar, said push weight pressure of the stylus bar it is set in vibratory motion at useful acoustic frequencies of the bass range, and through the cooperation of said vibrating mass with the stiffness of the stylus bar and the resilient elements connected therewith, the compliance of suspension of the push weight is considerably greater than the compliance of the stylus bar andhthe resilient elements connected there wit RUDOLF GOLDSCHMIDT.

' stylus bar supported with respect to said cas' V having such a mass that through the back 

